ARC Centre of Excellence for Nanoscale BioPhotonics & School of Science, ‡School of Engineering, and §RMIT Microscopy and Microanalysis Facility (RMMF), RMIT University , Melbourne, VIC 3001, Australia.
Department of Chemistry and ⊥Department of Materials Science & Engineering, Missouri University of Science & Technology , Rolla, Missouri 65409, United States.
ACS Nano. 2017 Nov 28;11(11):10924-10934. doi: 10.1021/acsnano.7b04647. Epub 2017 Nov 3.
Detonation nanodiamonds (DNDs) have unique physical and chemical properties that make them invaluable in many applications. However, DNDs are generally assumed to show weak fluorescence, if any, unless chemically modified with organic molecules. We demonstrate that detonation nanodiamonds exhibit significant and excitation-wavelength-dependent fluorescence from the visible to the near-infrared spectral region above 800 nm, even without the engraftment of organic molecules to their surfaces. We show that this fluorescence depends on the surface functionality of the DND particles. The investigated functionalized DNDs, produced from the same purified DND as well as the as-received polyfunctional starting material, are hydrogen, hydroxyl, carboxyl, ethylenediamine, and octadecylamine-terminated. All DNDs are investigated in solution and on a silicon wafer substrate and compared to fluorescent high-pressure high-temperature nanodiamonds. The brightest fluorescence is observed from octadecylamine-functionalized particles and is more than 100 times brighter than the least fluorescent particles, carboxylated DNDs. The majority of photons emitted by all particle types likely originates from non-diamond carbon. However, we locally find bright and photostable fluorescence from nitrogen-vacancy centers in diamond in hydrogenated, hydroxylated, and carboxylated detonation nanodiamonds. Our results contribute to understanding the effects of surface chemistry on the fluorescence of DNDs and enable the exploration of the fluorescent properties of DNDs for applications in theranostics as nontoxic fluorescent labels, sensors, nanoscale tracers, and many others where chemically stable and brightly fluorescent nanoparticles with tailorable surface chemistry are needed.
爆轰纳米金刚石（DND）具有独特的物理和化学性质，使其在许多应用中具有极高的价值。然而，除非与有机分子进行化学修饰，否则通常认为 DND 具有较弱的荧光，如果有的话。我们证明，即使没有将有机分子嫁接到其表面上，DND 也会在 800nm 以上的可见到近红外光谱区域显示出显著的、与激发波长相关的荧光，甚至在没有进行化学修饰的情况下也是如此。我们表明，这种荧光取决于 DND 颗粒的表面功能。所研究的功能化 DND 是由相同的经过纯化的 DND 以及收到的多官能起始材料生产的，它们分别是氢、羟基、羧基、乙二胺和十八烷基胺封端的。所有 DND 都在溶液中和硅晶片衬底上进行了研究，并与荧光高压高温纳米金刚石进行了比较。观察到的最亮荧光来自十八烷基胺功能化的颗粒，比最不荧光的颗粒，即羧基化 DND，亮 100 多倍。所有颗粒类型发射的大多数光子可能源自非金刚石碳。然而，我们在氢化、羟基化和羧基化的爆轰纳米金刚石中局部发现了来自金刚石中氮空位中心的明亮和光稳定荧光。我们的结果有助于理解表面化学对 DND 荧光的影响，并能够探索 DND 的荧光特性，将其用于治疗诊断学作为无毒荧光标记物、传感器、纳米级示踪剂以及许多其他需要具有可定制表面化学性质的化学稳定和明亮荧光纳米颗粒的应用中。
